An oropharyngeal tube is fitted to a patient after intubation by a tracheal tube and serves a number of purposes:
firstly it is intended to keep the airway open artificially and secondly to allow a cannula to be introduced at any time via the tube for the purpose of aspirating secretions, and furthermore, the tube should act as a bite block to prevent the inserted tracheal tube from being squeezed off or even bitten off. PA1 The Berman type has an open cross-section, generally a T or double-T profile. Since it is not possible to incorporate a bite block, this oropharyngeal tube is always made of a hard material. PA1 The Guedel type has a closed, generally transverse oval cross-sectional shape. Either it consists entirely of hard material or the actual tube consists of soft rubber or plastics, it being necessary to provide in the region of the straight portion a bite block of hard material which is generally a separate part that is pushed over the actual tube. Such oropharyngeal tubes are described, for example, in the January 1978 edition of the journal "Health Devices" in the article "Artificial Airways" starting on page 67. PA1 The closed cross-sectional shape of the Guedel type gives rise to problems with the cleaning of the tube for reuse, since it is very difficult to monitor the state of cleanliness. PA1 1. gives rise to poor throughflow rates, PA1 2. creates a contamination site with the risk of infection, PA1 3. gives rise to re-use problems because of the poor scope for cleaning, and PA1 4. makes it relatively difficult to insert an aspiration catheter.
In addition, the oropharyngeal tube should, as far as possible, hold the tongue and prevent it from falling back and closing the airways. This results in the anatomical shape of the tube which comprises, in succession as seen from the side, a transverse securing flange, which is located externally on the patient's lips, an adjoining short, substantially straight portion and in turn, adjoining the latter, a long, curved portion.
There are two fundamentally different types of pharyngeal tube:
Furthermore, it is known to use such a tube also for securing the inserted tracheal tube, in that the holding means for the oropharyngeal tube simultaneously holds the tracheal tube.
Such a solution, in which the holding means for the two tubes comprises a rubber band extending around the patient's neck, is described in an article from "Der Anasthesit" (The Anaesthetist), Vol. 13, part 5, May 1964, pages 172 and 173, Springer-Verlag, Berlin, under the title "Eine einfache Haltevorrichtung fur Endotracheal-Katheter" (A simple holding device for endotracheal catheters) by J. Schara, but the oropharyngeal tube used therein is a known Guedel tube supplemented by an advantageous holding means.
The known oropharyngeal tubes have a number of disadvantages:
Putting together the actual tube and an additional bite block is disadvantageous, since the internal diameter is not uniform and therefore there is a step between the bite block and the tube which
As a result of its cross-sectional shape the Berman type has a large number of free edges which, because it always has to be made of hard material, can easily result in injury to the patient.
The described holding means also has shortcomings, since every time the holding means for the oropharyngeal tube is released the tracheal tube is automatically also detached from its securing means, so that in such a case the tracheal tube can very easily become dislodged or slip out. The greatest disadvantage is, however, that access to the mouth for cleaning purposes is almost completely blocked, and aspiration is difficult to carry out, even via the tube. From the point of view of manufacture, this tube with the band is far too expensive.
It is an object of the present invention, therefore, to provide an oropharyngeal tube that is simple and risk-free in use, that is re-usable but is nevertheless simple and inexpensive to produce and, furthermore, enables the tracheal tube to be reliably secured.
According to the invention, the oropharyngeal device comprises an extended body having a comparatively shorter approximately straight portion and a comparatively longer curved portion adjoining the straight portion, the extended body having a substantially constant U-shaped transverse cross-section along an entire length thereof to provide a U-shaped opening extending along one side thereof; a transverse securing flange attached to an end of the straight portion remote from the curved portion; and a hard bite block formed integrally with the extended body and located in the vicinity of the straight portion. The bite block is made of a material also used for the extend body. One side of the transverse securing flange is provided with a U-shaped first recess conforming to the U-shaped transverse cross-section of the extended body and a second recess in a side of the securing flange remote from the side having the U-shaped first recess. The U-shaped first recess is positioned in the securing flange to provide a mouth for the U-shaped opening. The second recess is C-shaped and is dimensioned so that an endotracheal tube can be snapped therein and held fixed therein.
In a preferred embodiment of the invention the extended body has a wall thickness such that the tube body is elastic over the entire length thereof but cannot at least cannot be closed by compression or compressed in operation. Preferably the wall thickness of the straight portion is twice the wall thickness of the curved portion.
The extended body in an additional embodiment can have a longitudinally extending advantageously concave channel on a side opposite to the U-shaped opening, the channel having a base in alignment with a base of the C-shaped second recess.
Advantageously a smallest distance between the longitudinally extending channel and the U-shaped opening of the extended body is greater than a wall thickness of the extended body. Also in a preferred embodiment a height of the cross-section in the straight region of the extended body is greater in the vicinity of the smallest distance than in the vicinity of the U-shaped opening.
At least one perpendicularly projecting extension piece can be provided at the base of the C-shaped second recess extending from a side of the transverse securing flange remote from the extended body. The extension piece can have a length approximately equal to at least a width of a plaster strip and has a thickened portion at a free end thereof. The device can also have two fastening means for insertion into a fastening band, the fastening means being attached to the transverse securing flange and extending from a side of the securing flange remote from the extended body. Each of the fastening means has a projecting nipple protruding above and below a center of the transverse securing flange and the transverse securing flange is provided with two eyelets through which the fastening band can be passed.
Because the device of the invention is closed on one side and is open on the other side, firstly it is possible to insert it easily and with little risk of injury and, secondly, the open side allows the inside surface to be cleaned simply and thoroughly. Because the inside surface is constant and U-shaped, an aspiration catheter can be introduced into the tube very easily, that is to say with little resistance.
In contrast, in the known tubes or devices the inside surface is reduced in the region of the bite block.
The fact that the bite block is made of the same material as the whole device and is formed integrally therewith simplifies and reduces the cost of manufacture which can then be effected using an injection molding process.
The material chosen is a plastics material which has adequate resistance where the material is thicker, such as in the region of the bite block, but which enables the material thickness chosen for the curved portion of the extended body to be such that there the extended body is elastic in its longitudinal direction, that is to say deviating from the curved shape of its rest condition, while the U-shaped cross-section cannot be deformed by any action of the intubated patient, that is to say there is no risk of this artificial airway becoming compressed.
The second recess in the securing flange and the C-shape thereof allows a tracheal tube to be pushed in and locked into place. In addition to this holding means, the tracheal tube can be secured, by strips of plaster, to a corresponding extension piece extending outwards from the securing flange on the side remote from the extended body. The length thereof must correspond to at least the width of the strip of plaster and there is preferably a thickened portion on the free end of the extension piece to prevent the plaster strip from slipping off.
The secure position of the tracheal tube on the oropharyngeal tube is further increased by a channel extending in the longitudinal direction on the narrow side of the central portion, which channel is located on the narrow side opposite the U-shaped inside surface and in which channel a tracheal tube that is pressed into the C-shaped recess of the securing flange comes to rest. The channel has a curved cross-sectional shape the base of which is in alignment with the base of the C-shaped recess in the securing flange.
Bite protection is achieved by providing that the material thickness in the region of the central portion between the U-shaped inside surface and the channel is always greater than the material thickness in the region of the curved portion. In addition, the cross-section in this central portion, seen in elevation, is greater than at the side in the region of the U-shaped inside surface.
Furthermore, the extended body according to the invention can be fastened using securing devices, preferably using nipples that project forwards from the securing flange, by means of a rubber band around the rear of the head or neck of the patient. A tracheal tube that is rigidly connected to the oropharyngeal extended body in the described manner is also securely held thereby.